The stamp duty issue is true. WA is the only state that bases stamp duty paid on a new or demo car at the full RRP, regardless,of discount. However, Holden produces a 'revised RRP' which takes into account any promotions that might be running at the time, which lowers the price which stamp duty is paid on, I.e. If RRP is $54,990 but there is a campaign price advertised at $49,990 drive away for instance, the revised RRP becomes about $46,000. The issue them comes when it goes from one month to the next, because if you don't take delivery on the month you signed up and the bonuses drop or the price goes up, then the stamp duty is calculated at a higher price, costing the dealer more money.
The demo thing doesn't really mean anything. It sounds like you got a great deal and in order to do that the dealer had to claim a demo bonus from Holden. I'm surprised they didn't just reprint the rego papers with your name on them and then you would have been none the wiser. They just have to licence it in their name initially to keep Holden happy and then they would have instantly transferred it over to your name before you picked it up.
It's a communication issue really. They should have told you that in order to get that price they needed to register it before the end of the month in their name first and then transfer it over in order to get the extra money from Holden.
